Electrochemical cells having semi-solid electrodes and methods of manufacturing the same

ABSTRACT

Embodiments described herein relate generally to electrochemical cells having semi-solid electrodes that are coated on only one side of a current collector. In some embodiments, an electrochemical cell includes a semi-solid positive electrode coated on only one side of a positive current collector and a semi-solid negative electrode coated on only one side of a negative current collector. A separator is disposed between the semi-solid positive electrode and the semi-solid negative electrode. At least one of the semi-solid positive electrode and the semi-solid negative electrode can have a thickness of at least about 250 μm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/821,241, filed Mar. 17, 2020, now U.S. Pat. No. 10,886,521 and titled“Electrochemical Cells Having Semi-Solid Electrodes and Methods ofManufacturing the Same,” which is a continuation of U.S. patentapplication Ser. No. 14/932,153, filed Nov. 4, 2015, now U.S. Pat. No.10,637,038 and titled “Electrochemical Cells Having Semi-SolidElectrodes and Methods of Manufacturing the Same,” which claims priorityto and the benefit of U.S. Provisional Patent Application Ser. No.62/075,373, filed Nov. 5, 2014 and titled “Electrochemical Cells HavingSemi-Solid Electrodes and Methods of Manufacturing the Same,” thedisclosures of which are hereby incorporated by reference in its theirentirety.

BACKGROUND

Embodiments described herein relate generally to electrochemical cellshaving semi-solid electrodes that are coated on only one side of currentcollectors, stacks of such electrochemical cells, and methods of formingsuch electrochemical cell stacks.

Batteries are typically constructed of solid electrodes, separators,electrolyte, and ancillary components such as, for example, packaging,thermal management, cell balancing, consolidation of electrical currentcarriers into terminals, and/or other such components. The electrodestypically include active materials, conductive materials, binders andother additives.

Some known methods for preparing batteries include coating a metallicsubstrate (e.g., a current collector) with slurry composed of an activematerial, a conductive additive, and a binding agent dissolved ordispersed in a solvent, evaporating the solvent, and calendering thedried solid matrix to a specified thickness. The electrodes are thencut, packaged with other components, infiltrated with electrolyte andthe entire package is then sealed.

Such known methods generally involve complicated and expensivemanufacturing steps such as casting the electrode and are only suitablefor electrodes of limited thickness, for example, less than 100 μm(final single sided coated thickness). These known methods for producingelectrodes of limited thickness result in batteries with lower capacity,lower energy density and a high ratio of inactive components to activematerials. Furthermore, the binders used in known electrode formulationscan increase tortuosity and decrease the ionic conductivity of theelectrode.

To increase the active material to inactive material ratio, conventionalelectrochemical cells are generally formed by coating the electrodeactive material (i.e., the anode formulation slurry and the cathodeformulation slurry) on both sides of a current collector. A separator isdisposed between the electrodes, i.e. the anode and cathode, to form aconventional electrochemical cell. A plurality of such electrochemicalcells can be stacked on top of each other, generally with a spacerdisposed therebetween, to form an electrochemical cell stack. While thispositively impacts the active material to inactive material ratio, itintroduces complications in the manufacturing process. Furthermore, thetime required to assemble the electrochemical battery can besignificant. This can increase the exposure of the electrode materialsto temperature fluctuations or humidity which can degrade the electrodematerials and thereby, the electronic properties of the electrodes.

Thus, it is an enduring goal of energy storage systems development todevelop new electrochemical batteries and electrodes that have longercycle life, increased energy density, charge capacity and overallperformance.

SUMMARY

Embodiments described herein relate generally to electrochemical cellshaving semi-solid electrodes that are coated on only one side of acurrent collector. In some embodiments, an electrochemical cell includesa semi-solid positive electrode coated on only one side of a positivecurrent collector and a semi-solid negative electrode coated on only oneside of a negative current collector. A separator is disposed betweenthe semi-solid positive electrode and the semi-solid negative electrode.At least one of the semi-solid positive electrode and the semi-solidnegative electrode can have a thickness of at least about 250 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an electrochemical cell accordingto an embodiment.

FIG. 2 is a perspective view of an electrochemical cell in a pouchaccording to an embodiment.

FIG. 3 shows the electrochemical cell of FIG. 2 , with a pouch removed.

FIG. 4 is an exploded view of the electrochemical cell of FIG. 3 .

FIG. 5 shows an electrochemical cell stack in a pouch that includes aplurality of electrochemical cells, according to an embodiment.

FIG. 6 shows the electrochemical cell stack of FIG. 5 with a pouchremoved.

FIG. 7 shows a side cross-section of the electrochemical cell stackshown of FIG. 5 , taken along the line AA as shown in FIG. 6 .

FIG. 8 is a perspective view of an electrochemical cell stack thatincludes one positive current collector and one negative currentcollector that have tabs which are substantially longer than the tabs ofthe remaining positive and negative current collectors, according to anembodiment.

FIG. 9 is a side view of a portion of the electrochemical cell stack ofFIG. 8 , shown by the arrow B in FIG. 8 .

FIG. 10 shows a schematic flow diagram of a method of forming anelectrochemical cell stack, according to an embodiment.

FIGS. 11A-11I illustrate steps of a process to manufacture anelectrochemical cell, according to an embodiment.

DETAILED DESCRIPTION

Consumer electronic batteries have gradually increased in energy densitywith the progress of lithium-ion battery technology. The stored energyor charge capacity of a manufactured battery is a function of: (1) theinherent charge capacity of the active material (mAh/g), (2) the volumeof the electrodes (cm³) (i.e., the product of the electrode thickness,electrode area, and number of layers (stacks)), and (3) the loading ofactive material in the electrode media (e.g., grams of active materialper cm³ of electrode media). Therefore, to enhance commercial appeal(e.g., increased energy density and decreased cost), it is generallydesirable to increase the areal charge capacity (mAh/cm²). The arealcharge capacity can be increased, for example, by utilizing activematerials that have a higher inherent charge capacity, increasingrelative percentage of active charge storing material (i.e., “loading”)in the overall electrode formulation, and/or increasing the relativepercentage of electrode material used in any given battery form factor.Said another way, increasing the ratio of active charge storingcomponents (e.g., the electrodes) to inactive components (e.g., theseparators and current collectors), increases the overall energy densityof the battery by eliminating or reducing components that are notcontributing to the overall performance of the battery. One way toaccomplish increasing the areal charge capacity, and therefore reducingthe relative percentage of inactive components, is by increasing thethickness of the electrodes.

Semi-solid electrodes described herein can be made: (i) thicker (e.g.,greater than 250 μm—up to 2,000 μm or even greater) due to the reducedtortuosity and higher electronic conductivity of the semi-solidelectrode, (ii) with higher loadings of active materials, and (iii) witha simplified manufacturing process utilizing less equipment. Thesesemi-solid electrodes can be formed in fixed or flowable configurationsand decrease the volume, mass and cost contributions of inactivecomponents with respect to active components, thereby enhancing thecommercial appeal of batteries made with the semi-solid electrodes. Insome embodiments, the semi-solid electrodes described herein arebinderless and/or do not use binders that are used in conventionalbattery manufacturing. Instead, the volume of the electrode normallyoccupied by binders in conventional electrodes, is now occupied by: 1)electrolyte, which has the effect of decreasing tortuosity andincreasing the total salt available for ion diffusion, therebycountering the salt depletion effects typical of thick conventionalelectrodes when used at high rate, 2) active material, which has theeffect of increasing the charge capacity of the battery, or 3)conductive additive, which has the effect of increasing the electronicconductivity of the electrode, thereby countering the high internalimpedance of thick conventional electrodes. The reduced tortuosity and ahigher electronic conductivity of the semi-solid electrodes describedherein, results in superior rate capability and charge capacity ofelectrochemical cells formed from the semi-solid electrodes.

Since the semi-solid electrodes described herein, can be madesubstantially thicker than conventional electrodes, the ratio of activematerials (i.e., the semi-solid cathode and/or anode) to inactivematerials (i.e. the current collector and separator) can be much higherin a battery formed from electrochemical cell stacks that includesemi-solid electrodes relative to a similar battery formed fromelectrochemical cell stacks that include conventional electrodes. Thissubstantially increases the overall charge capacity and energy densityof a battery that includes the semi-solid electrodes described herein.Examples of electrochemical cells utilizing thick semi-solid electrodesand various formulations thereof are described in U.S. Pat. No.8,993,159 (also referred to as “the '159 patent”), issued Mar. 31, 2015,entitled “Semi-Solid Electrodes Having High Rate Capability,” U.S.Patent Publication No. 2014/0315097 (also referred to as “the '097publication), filed Mar. 10, 2014, entitled “Asymmetric Battery Having aSemi-Solid Cathode and High Energy Density Anode,” and U.S. PatentPublication No. 2015/0024279 (also referred to as “the '279publication”) filed Jul. 21, 2014, entitled “Semi-Solid Electrodes withGel Polymer Additive,” the entire disclosures of which are herebyincorporated by reference.

The semi-solid electrodes described herein are formulated as a slurrysuch that the electrolyte is included in the slurry formulation. This isin contrast to conventional electrodes, for example calenderedelectrodes, where the electrolyte is generally added to theelectrochemical cell once the electrochemical cell has been disposed ina container, for example, a pouch or a can. Exposure of the semi-solidelectrodes to the ambient environments for longer periods of time canincrease evaporation of the electrolyte, thereby affecting physicalcharacteristics (e.g., flowability) and/or electronic characteristics(e.g., conductivity, charge capacity, energy density, etc.) of theelectrochemical cell. Moreover, moisture in the ambient environment canalso detrimentally affect the performance of the electrolyte. Thus, itwould be of benefit to assemble the electrochemical cell that includesthe semi-solid electrodes described herein, in the shortest amount oftime to limit electrolyte evaporation and/or degradation. In someinstances, however, disposing the semi-solid electrodes on both sides ofa current collector (e.g., a metal foil) can take a substantial amountof time. Moreover, to form an electrochemical cell stack from suchelectrochemical cells, a spacer is often disposed between adjacentelectrochemical cells, which can further increase the time that thesemi-solid electrodes included in the electrochemical cells are exposedto the ambient atmosphere.

Embodiments of electrochemical cells described herein include semi-solidelectrodes that are coated on only one side of current collectors.Coating only one side of the current collectors reduces themanufacturing complexity as well as the time associated with coatingboth sides of the current collectors. An electrochemical cell stack canthen easily be formed by stacking the electrochemical cells such thatthe current collectors of adjacent electrochemical cells abut eachother. For example, an uncoated side of a positive current collectorincluded in a first electrochemical cell can abut an uncoated side of apositive current collector included in a second electrochemical cell.Similarly, an uncoated side of a negative current collector included inthe first electrochemical cell can abut an uncoated side of a negativecurrent collector included in a third electrochemical cell, and so on.This can further reduce the amount of time used for forming theelectrochemical cell stack, thereby minimizing exposure of theelectrodes to ambient environment. The short assembly time required toform the electrochemical cell also reduces electrolyte evaporation andor degradation of the semi-solid electrodes due to water permeation canalso be minimized.

In some embodiments, an electrochemical cell includes a semi-solidpositive electrode coated on only one side of a positive currentcollector and a semi-solid negative electrode coated on only one side ofa negative current collector. An ion-permeable membrane is disposedbetween the semi-solid positive electrode and the semi-solid negativeelectrode. At least one of the semi-solid positive electrode and thesemi-solid negative electrode has a thickness of at least about 250 μm.In some embodiments, the positive current collector and/or the negativecurrent collector can include a metal foil, for example, an aluminumfoil or a copper foil. In some embodiments, the electrochemical cell canbe disposed in a vacuum sealed pouch.

In some embodiments, a method of forming an electrochemical cell stackincludes coating a semi-solid cathode on only one side of a positivecurrent collector and coating a semi-solid anode on only one side of anegative current collector. A separator is disposed between thesemi-solid cathode and the semi-solid anode to form a firstelectrochemical cell. A second electrochemical cell is formedsubstantially similar to the first electrochemical cell. Furthermore, athird electrochemical cell is formed substantially similar to the firstelectrochemical cell, and so on. The second electrochemical cell isdisposed on the first electrochemical cell such that an uncoated side ofa positive current collector of the second electrochemical cell isdisposed on an uncoated side of the positive current collector of thefirst electrochemical cell. Similarly, the third electrochemical cell isdisposed on the first electrochemical cell such that an uncoated side ofa negative current collector of the third electrochemical cell isdisposed on an uncoated side of the negative current collector of thefirst electrochemical cell, thereby forming the electrochemical cellstack. In some embodiments, the time period required to form theelectrochemical cell stack can be sufficiently reduced such that theevaporation of an electrolyte included in the semi-solid cathode and/orthe semi-solid anode of any of the first electrochemical cell, thesecond electrochemical cell, and the third electrochemical cell, isminimized.

The mixing and forming of a semi-solid electrode generally includes: (i)raw material conveyance and/or feeding, (ii) mixing, (iii) mixed slurryconveyance, (iv) dispensing and/or extruding, and (v) forming. In someembodiments, multiple steps in the process can be performed at the sametime and/or with the same piece of equipment. For example, the mixingand conveyance of the slurry can be performed at the same time with anextruder. Each step in the process can include one or more possibleembodiments. For example, each step in the process can be performedmanually or by any of a variety of process equipment. Each step can alsoinclude one or more sub-processes and, optionally, an inspection step tomonitor process quality.

In some embodiments, the process conditions can be selected to produce aprepared slurry having a mixing index of at least about 0.80, at leastabout 0.90, at least about 0.95, or at least about 0.975. In someembodiments, the process conditions can be selected to produce aprepared slurry having an electronic conductivity of at least about 10⁻⁶S/cm, at least about 10⁻⁵ S/cm, at least about 10⁻⁴ S/cm, at least about10⁻³ S/cm, or at least about 10⁻² S/cm. In some embodiments, the processconditions can be selected to produce a prepared slurry having anapparent viscosity at room temperature of less than about 100,000 Pa-s,less than about 10,000 Pa-s, or less than about 1,000 Pa-s, all at anapparent shear rate of 1,000 s⁻¹. In some embodiments, the processconditions can be selected to produce a prepared slurry having two ormore properties as described herein. Examples of systems and methodsthat can be used for preparing the semi-solid electrode compositionsdescribed herein are described in U.S. Patent publication No.2013/0337319 (also referred to as “the '319 publication”), filed Mar.15, 2013, entitled “Electrochemical Slurry Compositions and Methods forPreparing the Same,” the entire disclosure of which is herebyincorporated by reference.

As used herein, the term “about” and “approximately” generally mean plusor minus 10% of the value stated, e.g., about 250 μm would include 225μm to 275 μm, about 1,000 μm would include 900 μm to 1,100 μm.

As used herein, the term “semi-solid” refers to a material that is amixture of liquid and solid phases, for example, such as particlesuspension, colloidal suspension, emulsion, gel, or micelle.

As used herein, the terms “activated carbon network” and “networkedcarbon” relate to a general qualitative state of an electrode. Forexample, an electrode with an activated carbon network (or networkedcarbon) is such that the carbon particles within the electrode assume anindividual particle morphology and arrangement with respect to eachother that facilitates electrical contact and electrical conductivitybetween particles and through the thickness and length of the electrode.Conversely, the terms “unactivated carbon network” and “unnetworkedcarbon” relate to an electrode wherein the carbon particles either existas individual particle islands or multi-particle agglomerate islandsthat may not be sufficiently connected to provide adequate electricalconduction through the electrode.

FIG. 1 shows a schematic illustration of an electrochemical cell 100.The electrochemical cell 100 includes a positive current collector 110and a negative current collector 120. A semi-solid cathode 140 isdisposed on the positive current collector 110, and a semi-solid anode150 is disposed on the negative current collector 120. A separator 130is disposed between the semi-solid cathode 140 and the semi-solid anode150. At least one of the semi-solid cathode 140 and the semi-solid anode150 has a thickness of at least about 250 μm, for example, in the rangeof about 250 μm to about 2,000 μm.

The positive current collector 110 and the negative current collector120 can be any current collectors that are electronically conductive andare electrochemically inactive under the operating conditions of thecell. Typical current collectors for lithium cells include copper,aluminum, or titanium for the negative current collector 120 andaluminum for the positive current collector 110, in the form of sheetsor mesh, or any combination thereof. Current collector materials can beselected to be stable at the operating potentials of the semi-solidcathode 140 and the semi-solid anode 150 of the electrochemical cell100. For example, in non-aqueous lithium systems, the positive currentcollector 110 can include aluminum, or aluminum coated with conductivematerial that does not electrochemically dissolve at operatingpotentials of 2.5-5.0V with respect to Li/Li⁺. Such materials includeplatinum, gold, nickel, conductive metal oxides such as vanadium oxide,and carbon. The negative current collector 120 can include copper orother metals that do not form alloys or intermetallic compounds withlithium, carbon, and/or coatings comprising such materials disposed onanother conductor. Each of the positive current collector 110 and thenegative current collector 120 can have a thickness of less than about20 microns, for example, about 1 micron, 2 microns, 3 microns, 4microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, 10microns, 12 microns, 14 microns, 16 microns, or 18 microns, inclusive ofall ranges therebetween. Use of such thin positive current collector 110and negative current collector 120 can substantially reduce the cost andoverall weight of the electrochemical cell 100.

The semi-solid cathode 140 and the semi-solid anode 150 included in theelectrochemical cell 100 are separated by a separator 130. The separator130 can be any conventional membrane that is capable of ion transport,i.e., an ion-permeable membrane. In some embodiments, the separator 130is a liquid impermeable membrane that permits the transport of ionstherethrough, namely a solid or gel ionic conductor. In some embodimentsthe separator 130 is a porous polymer membrane infused with a liquidelectrolyte that allows for the shuttling of ions between the semi-solidcathode 140 and the semi-solid anode 150 electroactive materials, whilepreventing the transfer of electrons. In some embodiments, the separator130 is a microporous membrane that prevents particles forming thesemi-solid cathode 140 and the semi-solid anode 150 compositions fromcrossing the membrane. In some embodiments, the separator 130 is asingle or multilayer microporous separator, optionally with the abilityto fuse or “shut down” above a certain temperature so that it no longertransmits working ions, of the type used in the lithium ion batteryindustry and well-known to those skilled in the art. In someembodiments, the separator 130 can include a polyethyleneoxide (PEO)polymer in which a lithium salt is complexed to provide lithiumconductivity, or Nafion™ membranes which are proton conductors. Forexample, PEO based electrolytes can be used as the separator 130, whichis pinhole-free and a solid ionic conductor, optionally stabilized withother membranes such as glass fiber separators as supporting layers. PEOcan also be used as a slurry stabilizer, dispersant, etc. in thepositive or negative redox compositions. PEO is stable in contact withtypical alkyl carbonate-based electrolytes. This can be especiallyuseful in phosphate-based cell chemistries with cell potential at thepositive electrode that is less than about 3.6 V with respect to Limetal. The operating temperature of the redox cell can be elevated asnecessary to improve the ionic conductivity of the membrane.

The semi-solid cathode 140 can include an ion-storing solid phasematerial which can include, for example, an active material and/or aconductive material. The quantity of the ion-storing solid phasematerial can be in the range of about 0% to about 80% by volume. Thecathode 140 can include an active material such as, for example, alithium bearing compound (e.g., Lithium Iron Phosphate (LFP), LiCoO₂,LiCoO₂ doped with Mg, LiNiO₂, Li(Ni, Co, Al)O₂ (known as “NCA”), Li(Ni,Mn, Co)O₂ (known as “NMC”), LiMn₂O₄ and its derivatives, etc.). Thecathode 140 can also include a conductive material such as, for example,graphite, carbon powder, pyrolytic carbon, carbon black, carbon fibers,carbon microfibers, carbon nanotubes (CNTs), single walled CNTs, multiwalled CNTs, fullerene carbons including “bucky balls,” graphene sheetsand/or aggregate of graphene sheets, any other conductive material,alloys or combination thereof. The cathode 140 can also include anon-aqueous liquid electrolyte such as, for example, ethylene carbonate,dimethyl carbonate, diethyl carbonate, SSDE, or any other electrolytedescribed herein or combination thereof.

In some embodiment, the semi-solid anode 150 can also include anion-storing solid phase material which can include, for example, anactive material and/or a conductive material. The quantity of theion-storing solid phase material can be in the range of about 0% toabout 80% by volume. The semi-solid anode 150 can include an anodeactive material such as, for example, lithium metal, carbon,lithium-intercalated carbon, lithium nitrides, lithium alloys andlithium alloy forming compounds of silicon, bismuth, boron, gallium,indium, zinc, tin, tin oxide, antimony, aluminum, titanium oxide,molybdenum, germanium, manganese, niobium, vanadium, tantalum, gold,platinum, iron, copper, chromium, nickel, cobalt, zirconium, yttrium,molybdenum oxide, germanium oxide, silicon oxide, silicon carbide, anyother materials or alloys thereof, and any other combination thereof.

The semi-solid anode 150 can also include a conductive material whichcan be a carbonaceous material such as, for example, graphite, carbonpowder, pyrolytic carbon, carbon black, carbon fibers, carbonmicrofibers, carbon nanotubes (CNTs), single walled CNTs, multi walledCNTs, fullerene carbons including “bucky balls”, graphene sheets and/oraggregate of graphene sheets, any other carbonaceous material orcombination thereof. In some embodiments, the semi-solid anode 150 canalso include a non-aqueous liquid electrolyte such as, for example,ethylene carbonate, dimethyl carbonate, diethyl carbonate, or any otherelectrolyte described herein or combination thereof.

In some embodiments, the semi-solid cathode 140 and/or the semi-solidanode 150 can include active materials and optionally conductivematerials in particulate form suspended in a non-aqueous liquidelectrolyte. In some embodiments, the semi-solid cathode 140 and/or thesemi-solid anode 150 particles (e.g., cathodic or anodic particles) canhave an effective diameter of at least about 1 μm. In some embodiments,the cathodic or anodic particles have an effective diameter betweenabout 1 μm and about 10 μm. In some embodiments, the cathodic or anodicparticles have an effective diameter of at least about 10 μm or more. Insome embodiments, the cathodic or anodic particles have an effectivediameter of less than about 1 μm. In some embodiments, the cathodic oranodic particles have an effective diameter of less than about 0.5 μm.In some embodiments, the cathodic or anodic particles have an effectivediameter of less than about 0.25 μm. In some embodiments, the cathodicor anodic particles have an effective diameter of less than about 0.1μm. In some embodiments, the cathodic or anodic particles have aneffective diameter of less than about 0.05 μm. In other embodiments, thecathodic or anodic particles have an effective diameter of less thanabout 0.01 μm.

In some embodiments, the semi-solid cathode 140 can include about 20% toabout 80% by volume of an active material. In some embodiments, thesemi-solid cathode 140 can include about 40% to about 75% by volume,about 50% to about 75% by volume, about 60% to about 75% by volume, orabout 60% to about 80% by volume of an active material.

In some embodiments, the semi-solid cathode 140 can include about 0% toabout 25% by volume of a conductive material. In some embodiments, thesemi-solid cathode 140 can include about 1.0% to about 6% by volume,about 6% to about 12%, or about 2% to about 15% by volume of aconductive material.

In some embodiments, the semi-solid cathode 140 can include about 20% toabout 70% by volume of an electrolyte. In some embodiments, thesemi-solid cathode 140 can include about 30% to about 60%, about 40% toabout 50%, or about 20% to about 40% by volume of an electrolyte.

In some embodiments, the semi-solid anode 150 can include about 20% toabout 80% by volume of an active material. In some embodiments, thesemi-solid anode 150 can include about 40% to about 75% by volume, about50% to about 75%, about 60% to about 75%, or about 60% to about 80% byvolume of an active material.

In some embodiments, the semi-solid anode 150 can include about 0% toabout 20% by volume of a conductive material. In some embodiments, thesemi-solid anode 150 can include about 1% to about 10%, 1% to about 6%,about 0.5% to about 2% by volume, about 2% to about 6%, or about 2% toabout 4% by volume of a conductive material.

In some embodiments, the semi-solid anode 150 can include about 20% toabout 70% by volume of an electrolyte. In some embodiments, thesemi-solid anode 150 can include about 30% to about 60%, about 40% toabout 50%, or about 20% to about 40% by volume of an electrolyte.

Examples of active materials, conductive materials, and/or electrolytesthat can be used in the semi-solid cathode 140 and/or the semi-solidanode 150 compositions, various formulations thereof, andelectrochemical cells formed therefrom, are described in the '159patent, U.S. Pat. No. 8,722,226 (also referred to as “the 226 patent”),issued May 13, 2014, entitled “High Energy Density Redox Flow Device,”and U.S. Patent Publication No. 2011/0200848 (also referred to as “the'848 publication”), filed Dec. 16, 2010, entitled “High Energy DensityRedox Flow Device,” the entire disclosures of which are herebyincorporated by reference.

In some embodiments, the semi-solid anode 150 can also include about 1%to about 30% by volume of a high capacity material. Such high capacitymaterials can include, for example, silicon, bismuth, boron, gallium,indium, zinc, tin, antimony, aluminum, titanium oxide, molybdenum,germanium, manganese, niobium, vanadium, tantalum, iron, copper, gold,platinum, chromium, nickel, cobalt, zirconium, yttrium, molybdenumoxide, germanium oxide, silicon oxide, silicon carbide, any other highcapacity materials or alloys thereof, and any combination thereof. Insome embodiments, the semi-solid can include about 1% to about 5% byvolume, about 1% to about 10% by volume, or about 1% to about 20% byvolume of the high capacity material. Examples of high capacitymaterials that can be included in the semi-solid anode 150, variousformulations thereof and electrochemical cells formed therefrom, aredescribed in the '097 publication.

While described herein as including a semi-solid cathode 140 and asemi-solid anode 150, in some embodiments, the electrochemical cell 100can include only one semi-solid electrode. For example, in someembodiments, the cathode 140 can be a semi-solid cathode and the anode150 can be a conventional solid anode (e.g., a high capacity solidanode). Similarly, in some embodiments, the cathode 140 can be a solidcathode and the anode 150 can be semi-solid anode.

In some embodiments, the electrolyte included in the at least one of thesemi-solid cathode 140 and/or the semi-solid anode 150 can include about0.1% to about 1% by weight of a gel-polymer additive. Examples of gelpolymer additives that can be included in the semi-solid cathode 140and/or semi-solid anode 150 formulation, and electrochemical cellstherefrom are described in the '279 publication.

In some embodiments, the cathode 140 and/or anode 150 semi-solidsuspensions can initially be flowable, and can be caused to becomenon-flowable by “fixing”. In some embodiments, fixing can be performedby the action of photopolymerization. In some embodiments, fixing isperformed by action of electromagnetic radiation with wavelengths thatare transmitted by the unfilled positive and/or negative electroactivezones of the electrochemical cell 100 formed from a semi-solid cathodeand/or semi-solid anode. In some embodiments, the semi-solid suspensioncan be fixed by heating. In some embodiments, one or more additives areadded to the semi-solid suspensions to facilitate fixing.

In some embodiments, the injectable and flowable semi-solid cathode 140and/or semi-solid anode 150 is caused to become non-flowable by“plasticizing”. In some embodiments, the rheological properties of theinjectable and flowable semi-solid suspension are modified by theaddition of a thinner, a thickener, and/or a plasticizing agent. In someembodiments, these agents promote processability and help retaincompositional uniformity of the semi-solid suspension under flowingconditions and positive and negative electroactive zone fillingoperations. In some embodiments, one or more additives are added to theflowable semi-solid suspension to adjust its flow properties toaccommodate processing requirements.

Systems employing negative and/or positive ion-storage materials thatare storage hosts for working ions, meaning that said materials can takeup or release the working ion while all other constituents of thematerials remain substantially insoluble in the electrolyte, areparticularly advantageous as the electrolyte does not becomecontaminated with electrochemical composition products. In addition,systems employing negative and/or positive lithium ion-storage materialsare particularly advantageous when using non-aqueous electrochemicalcompositions.

In some embodiments, the semi-solid ion-storing redox compositionsinclude materials proven to work in conventional lithium-ion batteries.In some embodiments, the positive semi-solid electroactive materialcontains lithium positive electroactive materials and the lithiumcations are shuttled between the negative electrode and positiveelectrode, intercalating into solid, host particles suspended in aliquid electrolyte.

The semi-solid cathode 140 is coated on only one side of the positivecurrent collector 110. Similarly, the semi-solid anode 150 is coated ononly one side of the negative current collector 120. For example, thesemi-solid electrodes can be casted, drop coated, pressed, roll pressed,or otherwise disposed on the current collectors using any other suitablemethod. Coating the semi-solid electrodes on only one side of thecurrent collectors can substantially reduce the time period for formingthe electrochemical cell 100. This can substantially reduce evaporationof the electrolyte included in the semi-solid cathode 140 and/or thesemi-solid anode 150 slurry formulations. Furthermore, exposure of theelectrolyte to the moisture present in the ambient environment can beminimized, thereby preventing degradation of the electrolyte.

A plurality of the electrochemical cell 100 can be disposed in a cellstack to form an electrochemical cell stack. For example, theelectrochemical cell 100 can be a first electrochemical cell 100. Thecell stack can include a second electrochemical cell (not shown) and athird electrochemical cell (not shown). Each of the secondelectrochemical cell and the third electrochemical cell can besubstantially similar to the first electrochemical cell 100. An uncoatedsurface of a positive current collector 110 included in the secondelectrochemical cell can be disposed on an uncoated surface of thepositive current collector 110 included in first electrochemical cell100. Similarly, an uncoated surface of a negative current collector 120included in the third electrochemical cell can be disposed on anuncoated surface of the negative current collector 120 included in firstelectrochemical cell 100. Any number of electrochemical cells 100 can beincluded in the cell stack. Stacking the plurality of theelectrochemical cells 100 as described herein significantly reduces thetime required to form the electrochemical cell stack. This can minimizeevaporation and/or degradation of the electrolyte as described herein.

FIGS. 2-4 show an electrochemical cell 200 that includes a positivecurrent collector 210 and a negative current collector 220. A semi-solidcathode 240 is disposed on the positive current collector 210 and asemi-solid anode 250 is disposed on the negative current collector 220.A separator 230 is disposed between the semi-solid cathode 240 and thesemi-solid anode 250. The electrochemical cell 200 is disposed in apouch 260.

The positive current collector 210 can be formed from a metal foil, forexample, a copper or aluminum foil, or any other materials describedwith respect to the positive current collector 210 included in theelectrochemical cell 200. The positive current collector 210 can have athickness in the range of about 20 μm to about 40 μm, for example, about25 μm, about 30 μm, or about 35 μm, inclusive of all rangestherebetween. In some embodiments, the positive current collector 210can have a thickness of less than about 20 μm, for example, about 5 μm,6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 16 μm, or about 18 μm,inclusive of all ranges therebetween. The positive current collector 210includes a tab 212 that is coupled with a positive lead 214. In someembodiments, the tab 212 can be cut to a desired length for couplingwith the positive lead 214. The positive lead can be a strip of aconducting metal (e.g., copper or aluminum) which can be coupled to thetab 212 using any suitable method, for example, ultrasonic welding,clamping, crimping, adhesive tape, and the likes. A ring 216 is wrappedaround a portion of the positive lead 214 and is aligned with an edge ofthe pouch 260 when the electrochemical cell 200 is disposed in the pouch260. Thus when the pouch 260 is sealed, the ring 216 ensures that thepouch 260 is thermally sealable. The ring 216 can be formed from aninsulating material, for example a select plastic such as Surlyn, or anyother suitable material.

The negative current collector 220 can be formed from a metal foil, forexample, a copper or aluminum foil, or any other materials describedwith respect to the negative current collector 220 included in theelectrochemical cell 200. The negative current collector 220 can have athickness in the range of about 20 μm to about 40 μm, for example, about25 μm, about 30 μm, or about 35 μm, inclusive of all rangestherebetween. In some embodiments, the negative current collector 220can have a thickness of less than about 20 μm, for example, about 5 μm,6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 16 μm, or about 18 μm,inclusive of all ranges therebetween. The negative current collector 220also includes a tab 222 that is coupled with negative lead 224. In someembodiments, the tab 222 can be cut to a desired length for couplingwith the negative lead 224. The negative lead 224 can be substantiallysimilar to the positive lead 214, and is not described in further detailherein. A ring 226 is wrapped around a portion of the negative lead 224and is aligned with an edge of the pouch 260 when the electrochemicalcell 200 is disposed in the pouch 260. Thus when the pouch 260 issealed, the ring 226 ensures that the pouch 260 is thermally sealable.The ring 226 can be formed from an insulating material, for example aselect plastic such as Surlyn, or any other suitable material.

The separator 230 can be an ion-permeable membrane and can be formedfrom any of the materials described with respect to the separator 230included in the electrochemical cell 200. The separator 230 can have athickness of about 10 μm to about 30 μm, for example, about 15 μm, about20 μm, or about 25 μm, inclusive of all ranges therebetween.

The semi-solid cathode 240 is disposed, for example coated, on a firstsurface of the positive current collector 210 which is proximal to theseparator 230. A second surface of the positive current collector 210distal to the separator 230 is left uncoated. Similarly the semi-solidanode 250 is disposed, for example coated, on a first surface of thenegative current collector 220 which is proximal to the separator 230. Asecond surface of the negative current collector 220 distal to theseparator 230 is left uncoated. Said another way, the semi-solid cathode240 and the semi-solid anode 250 are coated on only one side of thepositive current collector 210 and the negative current collector 220,respectively. Coating only one side reduces the time required to preparethe electrochemical cell 200. This can reduce the evaporation and/ordegradation (e.g., due to ambient humidity) of an electrolyte includedin the semi-solid cathode 240 and/or the semi-solid anode 250formulations. The semi-solid cathode 240 and the semi-solid anode 250can be formulated using any components (e.g., active materials and/orconductive materials, electrolytes, additives, gel polymers, etc.) asdescribed with respect to the semi-solid cathode 140 and the semi-solidanode 150 included in the electrochemical cell 100, respectively.Moreover, each of the semi-solid cathode 240 and/or the semi-solid anode250 can have a thickness of at least about 250 μm. For example, thesemi-solid cathode 240 and/or the semi-solid anode 250 can have athickness in the range of about 250 μm to about 2,000 μm.

The prepared electrochemical cell 200 can be vacuum sealed in aprismatic pouch 260 which can provide hermetic isolation of theelectrochemical cell 200 materials from the environment. Thus, the pouch260 can serve to avoid leakage of hazardous materials such aselectrolyte solvents and/or corrosive salts to the ambient environment,and can prevent water and/or oxygen infiltration into the cell. Otherfunctions of the pouch 260 can include, for example, compressivepackaging of the internal layers, voltage isolation for safety andhandling, and mechanical protection of the electrochemical cell 200assembly.

Typical pouch materials can include laminates (e.g., multi-layersheets), formed into, for example, two or three solid film-like layersand bound together by adhesive. The word “laminate” as used herein canalso refer to layers of material that are not chemically adhered to oneanother. For example, the layers can be in areal contact with each otherand coupled using other coupling methods, such as, for example, heatsealing. In some embodiments, the pouch 260 can formed frompolypropylene, for example, cast propylene. In some embodiments, anelectrochemical cell can be formed having a casing or pouch thatincludes multi-layer laminate sheets that include at least a first orinner layer formed with a plastic material and a second layer formedwith an electronically conducting material such that the multi-layersheet can be used as an electrochemically functional element of thecell. For example, in some embodiments, the electronically conductingmaterial (e.g., metal foil) of a pouch can be used as a currentcollector for the cell. In some embodiments, the metal foil can be usedas a pass-through tab. Thus, the multi-layer or laminate sheet(s) of thecell pouch can be used as an electrochemically functional material ofthe cell, in addition to acting as a packaging material. Systems,devices, and methods of manufacturing an electrochemical cell having acasing or pouch that includes multi-layer laminate sheets are describedin U.S. Patent Publication No. 2015/0171406 (also referred to as “the'406 publication”), filed Nov. 17, 2014, entitled “Electrochemical Cellsand Methods of Manufacturing the Same,” the entire disclosure of whichis hereby incorporated by reference.

A plurality of electrochemical cells 200, or any other electrochemicalcells described herein can be disposed in an electrochemical cell stack,for example, to form an electrochemical battery. Referring now to FIGS.5-7 an electrochemical cell stack 3000 is shown that includes aplurality of electrochemical cells disposed therein. The electrochemicalcell stack 3000 can be disposed in a pouch 360, for example a vacuumsealed pouch which can be substantially similar to the pouch 260described with respect to FIGS. 2-4 , and therefore, is not described infurther detail herein.

Each of the plurality electrochemical cell included in theelectrochemical cell stack 3000, for example a second electrochemicalcell 300 b (FIG. 6 ) can be substantially similar to the electrochemicalcell 100, or 200. Each of the current collectors included in theplurality of electrochemical cells includes a tab. For example, as shownin FIG. 6 , a positive current collector 310 b (FIG. 7 ) of the secondelectrochemical cell 300 b includes a tab 312 b and a negative currentcollector 320 b of the second electrochemical cell 300 b includes a tab322 b. Each of the tabs of the positive current collectors included inthe plurality of electrochemical cells are coupled together in apositive bail 313, which is then coupled to a positive lead 314. In someembodiments, each of the tabs of the positive current collectors can bebent over one another to form the positive bail 313. In someembodiments, the tabs included in the positive bail 313 can be cut to adesired length for coupling with the positive lead 314. In someembodiments, the positive current collectors 310 and/or the negativecurrent collectors 320 included in the cells 300 disposed towards theinterior of the cells can have tabs that are substantially shorter thanthe tabs 312 of the positive current collectors 310 and/or the tabs 322of the negative current collectors 320 included in the outermostelectrochemical cells 300. For example, the tab of the positive currentcollector 310 c included in the electrochemical cell 300 c can besubstantially longer than the tabs of the positive current collectors310 a and 310 b included in the electrochemical cells 300 a and 300 b,respectively. Similarly, the tab of the negative current collector 320 aincluded in the electrochemical cell 300 a can be substantially longerthan the tabs of the negative current collectors 320 b and 320 cincluded in the electrochemical cells 300 b and 300 c, respectively. Insuch embodiments, the shorter tabs can be coupled to the longer tabs,for example, via ultrasonic welding, clamping, crimping, adhesive tape,and the likes to form the bail (i.e., the bails 313 and 323). The longertabs of the outermost positive current collector and the outermostnegative current collector (e.g., the positive current collector 310 cand the negative current collector 310 a) can then be coupled to thepositive lead 314 and the negative lead 324. In this manner, the amountof material required to form the tabs can be reduced, thereby reducingthe cost and/or overall weight of the electrochemical cells 300. In someembodiments, the tabs of the positive current collectors 310 and thenegative current collectors of the innermost electrochemical cells 300can be longer than tabs 310 and 320 of the positive current collectors310 and the negative current collectors 320 of the remainingelectrochemical cells included in the electrochemical cell stack 3000.In some embodiments, the positive current collector 310 and/or thenegative current collector 320 that includes the longer tab can besubstantially thicker than the positive current collectors 310 and/ornegative current collectors 320 included in the other electrochemicalcells 300 included in the electrochemical cell stack 3000. In someembodiments, each of the positive current collectors 310 and thenegative current collectors 320 can have tabs that can be sufficientlong (e.g., about the same length as the positive tab 312 and thenegative tab 322 of the outermost positive current collector 310 and theoutermost negative current collector 320, respectively) to extend out ofthe pouch 360. In such embodiments, for example, the tabs of the each ofthe positive current collectors 310 can be coupled together, forexample, via ultrasonic welding, clamping, crimping, adhesive tape, andthe likes to form a positive bail (e.g., the bail 313). Similarly, thetabs of the each of the negative current collectors 320 can be coupledtogether as described herein, to form a negative bail (e.g., the bail323). As described herein, the positive bail (including the tabs of eachof the positive current collectors) and the negative bail (including thetabs of each of the negative current collectors) can extend out of thepouch and can be used to electrically interface the electrochemical cellstack 3000. Said another way, in such embodiments, the electrochemicalcell stack 3000 can be electrically coupled to external electroniccomponents directly via the positive bail and the negative bail suchthat the positive lead 314 and the negative lead 324 are not included inthe electrochemical cell stack.

The positive lead 314 can be strip of a conducting metal (e.g., copperor aluminum) which can be coupled to the positive bail 313 using anysuitable method, for example, ultrasonic welding, clamping, crimping,adhesive tape, and the likes. A ring 316 is wrapped around a portion ofthe positive lead 314 and is aligned with an edge of the pouch 360 whenthe electrochemical cell 300 is disposed in the pouch 360. Thus when thepouch 360 is sealed, the ring 316 ensures that the pouch 360 isthermally sealable. The ring 316 can be formed from an insulatingmaterial, for example a select plastic such as Surlyn, or any othersuitable material. Similarly, each of the tabs of the negative currentcollectors included in the plurality of electrochemical cells arecoupled together in a negative bail 323, which is then coupled to anegative lead 324. In some embodiments, each of the tabs of the negativecurrent collectors can be bent over one another to form the negativebail 323. In some embodiments, the tabs included in the negative bail323 can be cut to a desired length for coupling with the positive lead314. The negative lead 324 can be substantially similar to the positivelead 314, and is therefore, not described in further detail herein.Furthermore, ring 326 is wrapped around a portion of the negative lead324 and is aligned with an edge of the pouch 360 when theelectrochemical cell 300 is disposed in the pouch 360. The ring 326 canbe substantially similar to the ring 316, and is therefore, notdescribed in further detail herein.

FIG. 7 shows the side cross-section of a portion of the electrochemicalcell stack 3000 taken along line AA (FIG. 6 ). The portion of theelectrochemical cell stack 3000 includes a first electrochemical cell300 a, the second electrochemical cell 300 b and a third electrochemicalcell 300 c. The first electrochemical cell 300 a includes a firstpositive current collector 310 a, a first negative current collector 320a and a first separator 330 a. A first semi-solid cathode 340 a isdisposed on only one side of the first positive current collector 310 athat faces the first separator 330 a. Similarly, a first semi-solidanode 350 a is disposed on only one side of the first negative currentcollector 320 a that faces the first separator 330 a. The firstseparator 330 a is disposed between the first semi-solid cathode 340 aand the first semi-solid anode 350 a.

The second electrochemical cell 300 b includes a second positive currentcollector 310 b, a second negative current collector 320 b and a secondseparator 330 b. A second semi-solid cathode 340 b is disposed on onlyone side of the second positive current collector 310 b that faces thesecond separator 330 b. Similarly, a second semi-solid anode 350 b isdisposed on only one side of the second negative current collector 320 bthat faces the second separator 330 b. The second separator 330 b isdisposed between the second semi-solid cathode 340 b and the secondsemi-solid anode 350 b.

The third electrochemical cell 300 c includes a third positive currentcollector 310 c, a third negative current collector 320 c and a thirdseparator 330 c. A third semi-solid cathode 340 c is disposed on onlyone side of the third positive current collector 310 c that faces thethird separator 330 c. Similarly, a third semi-solid anode 350 c isdisposed on only one side of the third negative current collector 320 cthat faces the third separator 330 c. The third separator 330 c isdisposed between the third semi-solid cathode 340 c and the thirdsemi-solid anode 350 c.

The first electrochemical cell 300 a, the second electrochemical cell300 b, and the third electrochemical cell 300 c can be substantiallysimilar to each other. The positive current collectors, the negativecurrent collectors, and the separators included in each of theelectrochemical cells included in the electrochemical cell stack 3000can be formed from any materials described with respect to the positivecurrent collector 110, the negative current collector 120, and theseparator 130 included in the electrochemical cell 100. Furthermore, thesemi-solid cathode and the semi-solid anode included in each of theelectrochemical cells of the electrochemical cell stack 3000 can beformulated using any materials or methods described with respect to thesemi-solid cathode 140 and the semi-solid anode 150 included in theelectrochemical cell 100.

The second electrochemical cell 300 b is disposed on the firstelectrochemical 300 a such that an uncoated side of the second positivecurrent collector 310 b is adjacent and abuts an uncoated side of thefirst positive current collector 310 a. Similarly, the thirdelectrochemical cell 300 c is disposed on the first electrochemical cell300 a such that an uncoated side of the third negative current collector320 c is adjacent to and abuts an uncoated side of the first negativecurrent collector 320 a. While the electrochemical cell stack 3000 isshown as including eight electrochemical cells (FIG. 6 ), any number ofelectrochemical cells can be included in the electrochemical cell stack3000. While not shown herein, in some embodiment, a spacer, for example,an electrical and/or heat insulating spacer can be disposed between eachadjacent electrochemical cell. In some embodiments, the spacer can beconfigured to apply a stack pressure on the each of the electrochemicalcells included in the electrochemical cell stack 3000. Suitable spacerscan include, for example, a foam pad, a rubber pad, a plastic sheet, apaper or cardboard strip, and the likes.

In comparison with conventional electrochemical cell stacks, theelectrochemical cells stack 3000 can be formed in a smaller period oftime. This can minimize evaporation and/or degradation of theelectrolyte, as described herein. The electrochemical cell stack 3000can have a smaller ratio of active material to inactive material, whencompared with a similar sized electrochemical cell stack that includesthe semi-solid electrodes described herein coated on both sides ofcurrent collectors. However, compared with conventional electrochemicalcell stacks, that include conventional electrodes coated on both sidesof current collectors, the electrochemical cell stack can still have ahigher ratio of active material to inactive material. This is becausethe semi-solid electrodes can be made much thicker, for example in therange of about 250 μm to about 2,000 μm, in comparison to conventionalelectrodes that can generally not be made thicker than about 200 μm.Thus, the electrochemical cell stack 3000 can yield a desired energydensity and charge capacity with a fewer number of electrochemical cells(e.g., the electrochemical cell 300) included in the electrochemicalcell stack 3000 in comparison with a conventional electrochemical cellstack that yields a comparable energy density and charge capacity.Furthermore, the single side coated electrochemical cells 300 includedin the electrochemical cell stack 300 can include safety or protectivefeatures that cannot be included in conventional cells. For example, asafety perimeter or wall can be disposed around the edges of the currentcollectors (i.e., the positive current collectors 310 and the negativecurrent collectors 320) included in the electrochemical cell stack 3000to protect the semi-solid cathode 230 and the semi-solid anode 240.Moreover, slight misalignment between adjacent electrochemical cellsincluded in the electrochemical cell stack 3000 can be tolerated suchthat electrochemical cell stack 3000 can be formed in a shorter amountof time as compared to conventional electrochemical cell stacks.

In some embodiments, an electrochemical cell stack can include aplurality of cell stacks which includes a plurality of positive andnegative current collectors. One of the plurality of positive currentcollectors and one of the plurality of negative current collectors canhave tabs which are substantially longer than the tabs of the remainingcurrent collectors and can extend out of the electrochemical cell pouchfor interface with external electronics such that no leads are required.For example, referring now to FIG. 8 , an electrochemical cell stack4000 is shown that includes a plurality of electrochemical cellsdisposed therein. The electrochemical cell stack 4000 can be disposed ina pouch (not shown), for example a vacuum sealed pouch which can besubstantially similar to the pouch 260 described with respect to FIGS.2-4 .

Each of the plurality electrochemical cell included in theelectrochemical cell stack 4000 can be substantially similar to theelectrochemical cell 100, 200, or 300, and is therefore not described infurther detail herein. Each of the current collectors included in theplurality of electrochemical cells includes a tab. For example, as shownin FIG. 8 , an outermost positive current collector 410 b can include atab 412 b which is substantially longer than the tabs of the remainingpositive current collectors. The tabs of the positive current collectorscan be coupled together in a bail 413 and coupled to each other using acoupling mechanism 413 such as, for example, ultrasonic welding,clamping, crimping, adhesive tape, and the likes. Similarly, anoutermost negative current collector 420 a can include a tab 422 a whichis substantially longer than the tabs of the remaining negative currentcollectors. The tabs of the negative current collectors can be coupledtogether in a bail 423 and coupled to each other using a couplingmechanism 425 such as, for example, ultrasonic welding, clamping,crimping, adhesive tape, and the likes. In this manner, each of the tabsof the positive current collectors and the negative current collectorsare electronically coupled to each other such that the tab 412 b of thepositive current collector 410 b, and the tab 422 a of the negativecurrent collector 420 b, each of which are substantially longer than theremaining tabs, extend out of the bail and out of the pouch. Thus, thepositive tab 412 b and the negative tab 422 a can be used for electronicinterface with external electronics such that any extra components(e.g., leads) are not used.

Expanding further, FIG. 9 shows a side view of a portion of theelectrochemical cell stack 4000 shown by the arrow B in FIG. 8 , whichincludes the bail of negative current collectors. The electrochemicalcell stack includes 8 cell stacks, each of which includes a positivecurrent collector and a negative current collector. As shown in FIG. 9 ,the electrochemical cell stack 4000 includes 8 negative currentcollectors 422 a-h. The current collectors are joined together in a bail423 and coupled to each other using a coupling mechanism 425, asdescribed herein. The negative tab 422 a of the negative currentcollector 420 a (FIG. 8 ) is substantially longer than the negative tabs422 b-h of the remaining negative current collectors. Therefore, the tab422 a can extend beyond the bail and out of the pouch used to packagethe electrochemical cell stack 4000. In this manner, the tab 422 a canbe used to interface with electrochemical cell stack 4000 with externalelectronics, such that each of the negative current collectors includedin the electrochemical cell stack 4000 is in electronic communicationwith external electronics via the tab 422 a. Thus, external couplingcomponents, for example, negative leads are not used which makesmanufacturing simpler and reduces cost.

FIG. 10 illustrates a flow diagram showing an exemplary method 400 forpreparing an electrochemical cell stack that includes a plurality ofelectrochemical cells. The method 400 includes coating a semi-solidcathode on one side of a positive current collector 402. The semi-solidcathode can include, for example, the semi-solid cathode 140, 240 or anyother semi-solid cathode described herein. Suitable positive currentcollectors can include, for example the positive current collector 110,210, or any other positive current collector described herein. Asemi-solid anode is then coated on only one side of a negative currentcollector 404. The semi-solid anode can include any of the semi-solidanodes described herein, for example, the semi-solid anode 150, 250, orany other semi-solid anode described herein. Suitable negative currentcollectors can include, for example, the negative current collector 120,220, or any other negative current collector described herein. Aseparator (e.g., the separator 130, 230, or any other separatordescribed herein) is disposed between the semi-solid cathode and thesemi-solid anode to form a first electrochemical cell 406. A secondelectrochemical cell is formed in substantially the same manner as thefirst electrochemical cell 408. Furthermore, a third electrochemicalcell is formed in substantially the same manner as the firstelectrochemical cell 410. Each of the first electrochemical cell, thesecond electrochemical cell, and the third electrochemical cell can besubstantially similar to the electrochemical cell 100, 200, or any otherelectrochemical cell described herein.

To form the electrochemical cell stack, the second electrochemical cellis disposed on the first electrochemical cell such that an uncoated sideof the positive current collector of the second electrochemical cell isdisposed on (e.g., adjacent to or abuts) an uncoated side the positivecurrent collector of the first electrochemical cell 412. Next, the thirdelectrochemical cell is disposed on (e.g., adjacent to or abuts) thefirst electrochemical cell such that an uncoated side of a negativecurrent collector of the third electrochemical cell is disposed on anuncoated side of the negative current collector of the firstelectrochemical cell to form the electrochemical cell stack. Theelectrochemical cell stack can be substantially similar to theelectrochemical cell stack 3000, or any other electrochemical cell stackdescribed herein. In some embodiments, the time period required to formthe electrochemical cell stack can be sufficiently small such that theevaporation of an electrolyte included in the semi-solid anode or thesemi-solid cathode of any of the first electrochemical cell, the secondelectrochemical cell, and the third electrochemical cell, issubstantially reduced.

In some embodiments, the method 400 can optionally include disposing afirst spacer between the positive current collector of the firstelectrochemical cell and the positive current collector of the secondelectrochemical cell and/or disposing a second spacer between thenegative current collector of the third electrochemical cell and thenegative current collector of the first electrochemical cell. The spacercan include a heat and/or electrically insulating material such as, forexample, a foam pad, a rubber pad, a plastic sheet, a paper or cardboardstrip, and the likes.

FIGS. 11A-11I illustrate various steps in a process of manufacturing anelectrochemical cell 500 having semi-solid electrodes that are coated ononly one side of a current collector, according to an embodiment. Asshown in. FIG. 11A, a frame 562 (also referred to as “spacer frame”) isdisposed onto a current collector 510, which includes a power connectiontab 512. The current collector 510 can be placed on a holder 565 (alsoreferred to herein as “current collector holder”), for example, that canoptionally apply vacuum via a plurality of small holes (not shown)across the surface of the holder 565 so as to hold the current collector510 in place. The frame 562 has an opening 575 which can expose theunderlying current collector 510 when placed on top of the currentcollector 510.

FIG. 11B illustrates an electrode slurry 540 being disposed onto theexposed portion of the current collector 510 defined by the opening 575of the frame 562. The opening 575 defines the surface area of thefinished electrode 540 and the thickness of the frame 562 defines thethickness of the finished electrode 540. FIGS. 11C and 11D show theelectrode slurry 540 being smoothed or spread along the surface of theexposed portion of the current collector 510. In some embodiments, ablade 580 (also referred to herein as “doctor blade”) or straight edgedinstrument can be used to spread the electrode slurry 540. In someembodiments, the blade 580 and/or the holder 565 can be operably coupledto a vibration source (not shown) so as to vibrate the blade 580 or theholder 565 during the electrode slurry 540 deposition or smoothing. Thevibration can facilitate dispersion of the semi-solid electrode material540 during or after the slurry deposition step.

Optionally, an instrument (not shown), such as for example, an opticalor any analytical tool using any of non-contact measurement techniques,including optical or laser interferometry, ellipsometry or optical orlaser scanning probe to inspect surface morphology and optionallymeasure surface uniformity (e.g., thickness) of the spread electrodeslurry 540. The non-contact instrument can be deployed in situ as theblade 580 spreads the electrode slurry 540.

After the electrode slurry 540 is spread, as shown in FIG. 11E, theframe 562 can be removed leaving only the portion of the electrode 540that has been spread onto the exposed portion of the current collector510. As illustrated in FIG. 11F, a separator 530 can be placed on theelectrode 540 such that the separator 530 is covering the electrode 540.

The manufacturing steps illustrated in FIGS. 11A-11F above cover thedeposition step of an electrode onto a current collector. By way ofexample, the electrode 540 can be a cathode and the current collector510 can be a positive current collector. The manufacturing steps shownin FIGS. 11A-11E can be repeated for disposing a semi-solid anode 550onto a negative current collector 520. However, the manufacturing stepillustrated in FIG. 11F is performed on only one of the semi-solidcathode deposition step or the semi-solid anode deposition step since asingle separator 530 is used in an electrochemical cell 500.

At shown in FIG. 11G, once both the semi-solid cathode 540 and thesemi-solid anode 550 are disposed onto their respective currentcollectors 510 and 520, they can be aligned so that the semi-solidcathode 540 and the semi-solid anode 550 are facing and on top of eachother as illustrated, only to be separated by the separator 530. Asshown, the semi-solid anode 550 cannot be seen as it is on the undersideof the negative current collector 520. The assembled electrode-stackresembles the illustration shown in FIG. 3 .

As shown best in FIG. 11H, the electrochemical cell 500 includes asingle stack of cathode-separator-anode that is disposed inside a pouch560, which is then vacuum 566 and heat 567 sealed to form the finishedelectrochemical cell 500 as shown at FIG. 11I. Whereas the positivecurrent collector 510 includes a power connection tab 512, the negativecurrent collector 520 includes a power connection tab 522. The finishedelectrochemical cell 500 in the pouch 560 can be substantially similarto the electrochemical cell 200 shown in FIG. 2 . In some embodiments, aplurality of electrochemical cells 500 can be stacked to form anelectrochemical cell stack, which can be substantially similar to theelectrochemical cell stack 3000 illustrated in FIGS. 5-7 .

While various embodiments of the system, methods and devices have beendescribed above, it should be understood that they have been presentedby way of example only, and not limitation. Where methods and stepsdescribed above indicate certain events occurring in certain order,those of ordinary skill in the art having the benefit of this disclosurewould recognize that the ordering of certain steps may be modified andsuch modification are in accordance with the variations of theinvention. Additionally, certain of the steps may be performedconcurrently in a parallel process when possible, as well as performedsequentially as described above. The embodiments have been particularlyshown and described, but it will be understood that various changes inform and details may be made.

For example, although various embodiments have been described as havingparticular features and/or combination of components, other embodimentsare possible having any combination or sub-combination of any featuresand/or components from any of the embodiments described herein. Forexample, although some embodiments of the electrochemical cells weredescribed as being prismatic, in other embodiments, the electrochemicalcells can be curved, bent, wavy, or have any other shape. In addition,the specific configurations of the various components can also bevaried. For example, the size and specific shape of the variouscomponents can be different than the embodiments shown, while stillproviding the functions as described herein.

The invention claimed is:
 1. An electrochemical cell stack, comprising:a first positive current collector having a first surface and a secondsurface; a first electrode disposed on the first surface of the firstpositive current collector; a second positive current collector disposedon the second surface of the first current collector, the secondpositive current collector contacting a majority of the second surfaceof the first current collector; a first negative current collectorhaving a first surface and a second surface; a second electrode disposedon the first surface of the first negative current collector; a secondnegative current collector disposed on the second surface of the firstnegative current collector; a first separator disposed between the firstelectrode and the second electrode, wherein at least one of the firstelectrode and the second electrode includes a semi-solid electrode; athird electrode disposed on a first surface of the second positivecurrent collector, a second surface of the second positive currentcollector coupled to the second surface of the first positive currentcollector; a fourth electrode disposed on a first surface of the secondnegative current collector, a second surface of the second negativecurrent collector coupled to the second surface of the first negativecurrent collector; a third positive current collector and a fifthelectrode disposed on a first surface of the third positive currentcollector; and a second separator disposed between the first surface ofthe third positive current collector and the first surface of the secondnegative current collector, the second separator separate from the firstseparator.
 2. The electrochemical cell stack of claim 1, furthercomprising: a third negative current collector and a sixth electrodedisposed on a first surface of the third negative current collector. 3.The electrochemical cell stack of claim 2, further comprising: a thirdseparator disposed between of the first surface of the third negativecurrent collector and the first surface of the second positive currentcollector, the third separator separate from the first separator and thesecond separator.
 4. The electrochemical cell stack of claim 1, whereinthe second surface of the second current collector is coupled to thesecond surface of the first current collector via a spacer.
 5. Theelectrochemical cell stack of claim 1, further comprising: a framedisposed around an outside edge of the semi-solid electrode.
 6. Anelectrochemical cell stack, comprising: a first positive currentcollector having a first surface and a second surface; a semi-solidcathode disposed on the first surface of the first positive currentcollector; a second positive current collector disposed on the secondsurface of the first current collector; a first negative currentcollector having a first surface and a second surface; an anode disposedon the first surface of the first negative current collector; a secondnegative current collector disposed on the second surface of the firstnegative current collector, the second negative current collectorcontacting a majority of the second surface of the first negativecurrent collector; a first separator disposed between the first surfaceof the first positive current collector and the first surface of thefirst negative current collector; a semi-solid cathode disposed on afirst surface of the second positive current collector, a second surfaceof the second positive current collector coupled to the second surfaceof the first positive current collector; an anode disposed on a firstsurface of the second negative current collector; a third positivecurrent collector and a semi-solid cathode disposed on a first surfaceof the third positive current collector, a second surface of the secondnegative current collector coupled to the second surface of the firstnegative current collector; and a second separator disposed between thefirst surface of the third positive current collector and the firstsurface of the second negative current collector, the second separatorseparate from the first separator.
 7. The electrochemical cell stack ofclaim 6, further comprising: a third negative current collector and ananode disposed on a first surface of the third negative currentcollector.
 8. The electrochemical cell stack of claim 7, furthercomprising: a third separator disposed between of the first surface ofthe third negative current collector and the first surface of the secondpositive current collector.
 9. The electrochemical cell stack of claim6, wherein the second surface of the second current collector is coupledto the second surface of the first current collector via a spacer. 10.The electrochemical cell stack of claim 6, further comprising: a framedisposed around an outside edge of the semi-solid cathode.
 11. Anelectrochemical cell stack, comprising: a first positive currentcollector having a first surface and a second surface; a cathodedisposed on the first surface of the first positive current collector; asecond positive current collector disposed on the second surface of thefirst positive current collector, the second positive current collectorcontacting a majority of the second surface of the first positivecurrent collector; a first negative current collector having a firstsurface and a second surface; a semi-solid anode disposed on the firstsurface of the negative current collector; a second negative currentcollector disposed on the second surface of the first negative currentcollector, the second negative current collector contacting a majorityof the second surface of the first negative current collector; a firstseparator disposed between the first surface of the first positivecurrent collector and the first surface of the first negative currentcollector; a cathode disposed on a first surface of the second positivecurrent collector; a semi-solid anode disposed on a first surface of thesecond negative current collector; a third positive current collectorand a cathode disposed on a first surface of the third positive currentcollector; and a second separator disposed between the first surface ofthe third positive current collector and the first surface of the secondnegative current collector, the second separator separate from the firstseparator.
 12. The electrochemical cell stack of claim 11, furthercomprising: a third separator disposed between the first surface of thethird positive current collector and the first surface of the secondnegative current collector, the third separator separate from the firstseparator and the second separator.
 13. The electrochemical cell stackof claim 12, further comprising: a third negative current collector anda semi-solid anode disposed on a first surface of the third negativecurrent collector.
 14. The electrochemical cell stack of claim 11,further comprising: a frame disposed around an outside edge of thesemi-solid anode.
 15. The electrochemical cell stack of claim 11,wherein the second surface of the second current collector is coupled tothe second surface of the first current collector via a spacer.